1. Field of the Invention
The present invention relates to performing a quick channel change when a Digital Multimedia Broadcasting (DMB) signal using a high compression technique, such as H.264, is retransmitted to an Internet Protocol (IP)-based wired/wireless network.
2. Description of the Related Art
Digital Multimedia Broadcasting (DMB) is a Korean system standard for a multimedia broadcasting service comprising video based on Digital Audio Broadcasting (DAB: Eureka-147). DAB is a European digital radio broadcasting standard for simultaneously providing a compact disk (CD)-level high quality audio service and a data service.
In order to receive the DMB broadcasting service, a separate DMB receiver is required, and a DMB signal cannot be received through an Internet Protocol (IP)-based wired/wireless network in which a DMB receiver does not exist.
As a technique for receipt of a DMB signal through an IP-based wired/wireless network, a method of IP encapsulation of Motion Picture Expert Group-2 Transport Stream (MPEG-2 TS)/MPEG-4 Synchronization Layer (SL) DMB data and transmitting the IP-encapsulated DMB data has been developed.
In a retransmission system using a packet method for a DMB service, based on this development, a terminal supporting the packet method without having a separate DMB receiver can receive DMB data from a device having a DMB data decoding function and view a DMB program.
However, in the DMB data retransmission system, a retransmission server transmits only data having a MPEG-2 TS header extracted after performing error correction code from among information regarding DMB data via an IP-based wired/wireless network. Thus, an IP-based terminal must decode DMB data received from the DMB data retransmission system by analyzing a header of each received stream. Accordingly, a complicated process is required for the IP-based terminal to select a channel of DMB data to be received.
FIG. 4 is a flowchart illustrating a conventional channel change method of a terminal receiving retransmitted data in a retransmission system using a packet method for a DMB service.
Referring to FIG. 4, according to the conventional channel change method, packet type data transformed to IP-based data is received in step 41. If a Program Association Table (PAT) exists in the received packet type data in step 42, it is determined in step 44 whether a Program Map Table (PMT) according to the PAT exists in the received packet type data. If the PAT does not exist in the received packet type data in step 42, the relevant PAT is searched for in step 43, and it is determined in step 44 whether the PMT according to the found PAT exists in the received packet type data.
If it is determined in step 44 that the PMT exists in the received packet type data, it is determined in step 46 whether SL data exists in the received packet type data. If it is determined in step 44 that the PMT does not exist in the received packet type data, the relevant PMT is searched for in step 45, and it is determined in step 46 whether SL data according to the found PMT exists in the received packet type data.
If it is determined in step 46 that the SL data exists in the received packet type data, an Audio/Video (AV) packet according to the SL data is executed in step 48. If it is determined in step 46 that the SL data does not exist in the received packet type data, relevant SL data is searched for in step 47, and an AV packet according to the found SL data is executed in step 48.
That is, when a terminal receiving retransmitted data performs a conventional channel change in the retransmission system using a packet method for a DMB service, since all procedures of processing PAT, PMT, and SL data must be performed every time a channel is changed, the channel change operation is complicated and requires a long time.